Binding of cellular protein(s) to U3 region of human T-cell leukemia virus type-I long terminal repeat.

The U3 region within the long terminal repeat (LTR) of human T-cell leukemia virus type-I (HTLV-I) contains elements responsible for transcriptional trans-activation. DNA-binding activities of nuclear proteins for each region of LTR were demonstrated using the gel retardation assay. The existence of cellular protein(s) specifically binding to the U3 region was demonstrated. Furthermore, the formation of the U3-protein(s) complex increased remarkably in HTLV-I-infected T-cells.